MRI compatible intrabody fluid transfer systems and related devices and methods

ABSTRACT

Systems and methods for transferring fluid to or from a subject use a set of MRI compatible components that can aspirate intrabody structure and/or fluids. The components include a device guide, a semi-rigid guide sheath configured to slidably extend through the device guide, a stylet releasable coupled to the guide sheath and extending a fixed distance out of a distal end thereof, and a cannula coupled to flexible tubing that is releasably interchangeably held in the guide sheath in lieu of the stylet.

RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalApplication Ser. No. 62/668,920, filed May 9, 2018, the contents ofwhich are hereby incorporated by reference as if recited in full herein.

FIELD OF THE INVENTION

The present invention relates generally to medical devices and systemsand, more particularly, to devices and systems for delivering and/orwithdrawing substances in vivo, and may be particularly suitable forMRI-guided aspiration procedures.

BACKGROUND

Various medical procedures require that a substance be aspirated ordelivered (e.g., infused) into a prescribed region of a patient, such asto a deep brain target. It may be important or critical that thesubstance be delivered with high accuracy to the target region in thepatient and without undue trauma to the patient.

For example, there are people that have abnormal structures that form inthe brain. These structures can be liquid or semi-liquid (soft tissue)in nature. Some examples are fluid-filled cysts, colloid cysts, andlarge blood clots. When these structures exert pressure on thesurrounding areas, various symptoms such as blurry vision, difficultyspeaking, or loss of coordination may occur.

Once it is determined that one of these structures is the cause of theproblem, physicians determine how to decompress the affected area. Insome cases, surgical resection is performed. However, for structuresthat are deep in the brain and/or extend deep into the brain, surgicalresection can be undesirable or not feasible.

One option is to aspirate fluid from the structure to debulk it.Debulking the structure can relieve pressure on the surrounding areas.This can be desirable as it can be performed in a less invasive mannerthan surgical resection. The current procedure, though, requires that asurgical navigation system be used with pre-op images to position anendoscope trochar, a biopsy needle, or some other aspirating device.Initial position can be important, as the surgeon will target a point inwhich a single aspiration attempt can withdraw a large percentage offluid.

Once the surgeon places the device, the intrabrain structure isaspirated. Afterward, the patient is transported to a CT scanner so thatthe surgeon can determine how much debulking of the structure wasaccomplished. If the surgeon thinks that further debulking is necessary,the patient is transported back to the surgical room where thenavigation procedure is repeated and more fluid is extracted. Thepatient is then again transported back to the CT scanner, and another CTscan is performed after the subsequent debulking procedure.

The conventional debulking process is costly, time-consuming, andpotentially exposes the patient to a higher risk of infection because ofthe transportation from room to room.

SUMMARY

It should be appreciated that this Summary is provided to introduce aselection of concepts in a simplified form, the concepts being furtherdescribed below in the Detailed Description. This Summary is notintended to identify key features or essential features of thisdisclosure, nor is it intended to limit the scope of the invention.

Embodiments of the invention are directed to MRI compatible fluidtransfer devices and systems for transferring fluid to or from a subjectand may be particularly suitable for aspiration procedures.

Embodiments of the invention are directed to an MRI compatible surgicaldevice that includes a semi-rigid polymeric cannula body coupled toflexible tubing. The cannula body has a longitudinally extending openthrough channel and is formed of medical grade polyimide tubing with awall thickness in a range of about 0.005-0.025 inches. The cannula bodyhas a maximal intrabody size in a range of about 10 F-16 F. A distal endof the flexible tubing or a proximal end of the cannula body includes aguide sheath clip connector with longitudinally extending handles. Upperend portions of the handles flex inward to pivot lower end portionsoutward to disengage a target device.

The wall thickness of the medical grade polyimide tubing can be in arange of about 0.009-0.010 inches.

Other embodiments are directed to an MRI compatible intrabody guidesheath that includes a semi-rigid polymeric guide sheath body. The guidesheath has an axially extending open through channel with opposingproximal and distal ends. In position, the distal end of the guidesheath extends a distance into a subject while the proximal end isexternal to the subject. The guide sheath body is formed of extrudedmedical grade PEEK and has a maximal outer diameter of between 12 Fr and19 Fr. The guide sheath body has a radially outwardly extending externalhub adjacent the proximal end. The distal end is tapered and the guidesheath body has a length in a range of 10-16 inches, a wall thickness ofabout 0.020 inches, and an inner diameter in a range of 0.168 inches and0.220 inches.

The guide sheath can include measurement indicia on an external wallthereof.

The guide measurement indicia can include or be a graduated scale ofdistance extending over a sub-length of the guide sheath body with asegment adjacent the distal end being devoid of the graduated scale.

The measurement indicia can include a graduated scale that starts at adistance value that is greater than 10 cm at a location spaced apartfrom the distal end in a range of 1-8 cm and extends to the proximalend.

The guide sheath can be in combination with a stylet releasably coupledto the guide sheath body. The stylet can have a guide sheath connectoron a proximal end portion thereof, wherein the guide sheath connector isa clip with longitudinally extending handles that extend a distanceabove the hub, and wherein upper end portions of the handles flex inwardto pivot lower end portions outward to disengage the hub.

Yet other embodiments are directed to surgical fluid transfer systemsthat include a device guide comprising an axially extending open throughchannel and a semi-rigid guide sheath. The guide sheath is configured toslidably extend through the open through channel of the device guide andhas an axially extending open through channel with opposing proximal anddistal ends. The guide sheath has a length that is longer than a lengthof the device guide. The guide sheath includes a radially outwardlyextending hub adjacent the proximal end. In position, the distal end ofthe guide sheath extends a distance into a subject while the proximalend is external to the subject. The systems also include a styletreleasably coupled to the guide sheath. When fully assembled to theguide sheath, the stylet extends through the open through channel of theguide sheath and has a distal end that extends a distance out of adistal end of the guide sheath. The stylet has an extruded polymericbody with a hollow core and a solid tapered tip. The stylet has aproximal end portion with a connector that releasably attaches to thehub. The systems further include a cannula coupled to flexible tubingand comprising longitudinally opposing proximal and distal ends. Theflexible tubing has a distal end that is sealably coupled to theproximal end of the cannula. In use, the flexible tubing and theproximal end of the cannula reside external to the subject. The cannulais releasably interchangeably coupled to the guide sheath, and, inposition, the cannula extends through the guide sheath and has a distalend that extends a distance out of the distal end of the guide sheath.

The guide sheath can include measurement indicia on an external wallthereof.

The connector can be a clip with longitudinally extending handles thatextend a distance above the hub. Upper end portions thereof can flexinward to pivot lower end portions outward to disengage the hub.

The distance that the stylet and the cannula extend out of the distalend of the guide sheath can be the same, optionally in a range of about3-5 mm.

The flexible tubing can have a luer lock connector on a proximal endthereof and a guide sheath connector on the distal end thereof.

The flexible tubing can have a guide sheath connector on a proximal endportion thereof that releasably attaches to the hub.

The guide sheath connector can be a clip with longitudinally extendinghandles that extend a distance above the hub. Upper end portions thereofcan flex inward to pivot lower end portions outward to disengage thehub.

The system can further include an adapter with a longitudinallyextending through channel. The adapter can have upper and lower spacedapart lock members. The guide sheath can be configured to extend throughthe adapter and the upper lock member can be configured to lock againstthe guide sheath.

The system can include a depth stop that slidably couples to the guidesheath and is adjustable along a length of the guide sheath. The depthstop can abut a top surface of the adapter to hold the guide sheath in afixed position.

The system can further include a trajectory guide adapted to mount to asubject. The trajectory guide can have a tubular support member with anopen through channel that holds the device guide and receives a bottomportion of the adapter.

The device guide, the guide sheath, the stylet and the cannula with theflexible tubing can all MRI compatible polymeric devices that can beprovided in a kit for an aspiration procedure.

Yet other embodiment are directed to an aspiration system that includes:a trajectory guide; a device guide held by the trajectory guide; anadapter with a longitudinally extending through channel and upper andlower lock members; a semi-rigid polymeric guide sheath with opposingproximal and distal ends and a longitudinally extending open throughchannel. The guide sheath further includes an outer wall with anoutwardly extending hub adjacent the proximal end. The guide sheathextends through the device guide and adapter. The upper lock member ofthe adapter is lockable against the guide sheath. The systems alsoinclude a stylet with a guide sheath connector on a proximal end portionthereof releasably attachable to the guide sheath. The stylet has apolymeric body with a closed tapered tip that extends a distance out ofthe distal end of the guide sheath. The system further includes asemi-rigid polymeric cannula coupled to flexible tubing. A distal end ofthe flexible tubing or a proximal end of the cannula comprises a guidesheath connector that is also, interchangeably, releasably attachable tothe guide sheath in place of the stylet. When coupled to the guidesheath, a distal end of the cannula extends a distance out of the distalend of the guide sheath.

The distal end of the cannula and the tip of the stylet can extend outof the distal end of the guide sheath a fixed common distance in a rangeof about 3-5 mm.

The system can also include a syringe coupled to a proximal end of theflexible tubing to thereby allow a user to aspirate fluid from thesubject through the cannula and flexible tubing.

The stylet can have an extruded polymeric body with a hollow core and asolid tapered tip.

The cannula can have a body of medical grade polyimide tubing with awall thickness in a range of about 0.005-0.025 inches, optionally in arange of about 0.009-0.010 inches. The cannula can have a maximalintrabody size of about 10 Fr-16 Fr, such as one of 10 Fr, 12 Fr, 14 Fror 16 Fr.

The system can further include a depth stop on the guide sheath residingbelow the hub.

The outer wall of the guide sheath can include external measurementindicia.

Yet other embodiments are directed to methods of removing fluid from atarget intrabody site, during an MRI guided surgical procedure. Themethods can include: (a) providing a set of MRI compatible componentscomprising a device guide, a semi-rigid guide sheath (optionally withmeasurement indicia) configured to slidably extend through the deviceguide, a stylet releasable coupled to the guide sheath and extending afixed distance out of a distal end thereto, and a cannula coupled toflexible tubing; attaching the device guide to a trajectory guidemounted to a subject, the trajectory guide defining an entry trajectoryaxis into the subject to a target site; (b) placing a depth stop at adesired location on the guide sheath, the desired location associatedwith measurement indicia calculated to place a distal end of the styletand a distal end of the cannula at the target site when the guide sheathis attached to the trajectory guide; (c) inserting the guide sheath andstylet, coupled together as an assembly, through the open channel of thedevice guide; (d) removing the stylet from the guide sheath; then (e)inserting the cannula into the guide sheath so that a distal end thereofresides at the target site; and (f) removing fluid from the target sitethrough the cannula and flexible tubing while the subject is in a magnetof an MR Scanner during the MRI guided surgical procedure.

It is noted that aspects of the invention described with respect to oneembodiment may be incorporated in a different embodiment although notspecifically described relative thereto. That is, all embodiments and/orfeatures of any embodiment can be combined in any way and/orcombination. Applicant reserves the right to change any originally filedclaim or file any new claim accordingly, including the right to be ableto amend any originally filed claim to depend from and/or incorporateany feature of any other claim although not originally claimed in thatmanner. These and other objects and/or aspects of the present inventionare explained in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an MRI-guided interventionalsystem in which embodiments of the present invention may be utilized.

FIG. 2 is a top view of an exemplary set of components for a medicalprocedure according to embodiments of the present invention.

FIG. 3 is a side perspective view of a trajectory guide coupled to asubject that can serially interchangeably hold a targeting cannula andone or more of the components shown in FIG. 2 according to embodimentsof the present invention.

FIG. 4 is a side perspective view of the trajectory guide shown in FIG.3 that slidably couples to the device guide of the devices shown in FIG.2 according to embodiments of the present invention.

FIGS. 5A and 5B are side perspective views of the trajectory guideholding the device shown in FIG. 4 and also coupled to the adapter shownin FIG. 2 according to embodiments of the present invention.

FIG. 5C is an enlarged view of the adapter shown in FIG. 2.

FIG. 5D is a section view taken along line 5D-5D in FIG. 5C, accordingto embodiments of the present invention.

FIG. 6A is an enlarged view of the guide sheath shown in FIG. 2.

FIG. 6B is an enlarged view of the guide sheath shown in FIG. 6A coupledto a depth stop according to embodiments of the present invention.

FIGS. 7A-7C are side perspective views of an exemplary sequence ofactions for attaching the guide sheath and stylet to the trajectoryguide shown in FIG. 3 according to embodiments of the present invention.

FIGS. 8A and 8B are enlarged partial views of the guide sheath andstylet shown in FIGS. 7A-7C illustrating an exemplary detachmentsequence of the stylet while the guide sheath remains in positioncoupled to the trajectory guide according to embodiments of the presentinvention.

FIGS. 9A and 9B are enlarged side perspective views of an exemplaryattachment sequence for attaching the guide cannula to the guide sheathheld by the trajectory guide according to embodiments of the presentinvention.

FIGS. 10A and 10B are side perspective views of flexible tubing attachedat one end to the guide sheath and attached or attachable to a syringeon the other end according to embodiments of the present invention.

FIG. 11 is a section view of an example stylet body according toembodiments of the present invention.

FIG. 12A is an end perspective view of a bore of a magnet with a fluiddelivery system in position according to embodiments of the presentinvention.

FIG. 12B is a schematic of a portion of the system shown in FIG. 12Aillustrating the radius of curvature allowed by the fluid deliverysystem according to embodiments of the present invention.

FIG. 13 is a schematic illustration of an example screen display of asurgical navigation system shown on a display according to embodimentsof the present invention.

FIG. 14 is a flow chart of example actions that can be carried outaccording to embodiments of the present invention.

DETAILED DESCRIPTION

The present invention now is described more fully hereinafter withreference to the accompanying drawings, in which some embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

Like numbers refer to like elements throughout. In the figures, thethickness of certain lines, layers, components, elements or features maybe exaggerated for clarity. The abbreviations “FIG.” and “Fig.” are usedinterchangeably with the word “Figure” to refer to the drawings.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, steps, operations, elements, components, and/or groupsthereof. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the specification andrelevant art and should not be interpreted in an idealized or overlyformal sense unless expressly so defined herein. Well-known functions orconstructions may not be described in detail for brevity and/or clarity.

It will be understood that when an element is referred to as being “on”,“attached” to, “connected” to, “coupled” with, “contacting”, etc.,another element, it can be directly on, attached to, connected to,coupled with or contacting the other element or intervening elements mayalso be present. In contrast, when an element is referred to as being,for example, “directly on”, “directly attached” to, “directly connected”to, “directly coupled” with or “directly contacting” another element,there are no intervening elements present. It will also be appreciatedby those of skill in the art that references to a structure or featurethat is disposed “adjacent” another feature may have portions thatoverlap or underlie the adjacent feature.

Spatially relative terms, such as “under,” “below,” “lower,” “over,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is inverted, elements described as “under” or “beneath” otherelements or features would then be oriented “over” the other elements orfeatures. Thus, the exemplary term “under” can encompass both anorientation of “over” and “under”. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Similarly, the terms“upwardly,” “downwardly,” “vertical,” “horizontal” and the like are usedherein for the purpose of explanation only unless specifically indicatedotherwise.

The term “about,” as used herein with respect to a value or number,means that the value or number can vary by +/−twenty percent (20%).

The term “monolithic” means that the component (e.g., needle) is formedof a single uniform material.

The term “MRI visible” means that a device is visible, directly orindirectly, in an MRI image. The visibility may be indicated by theincreased SNR of the MRI signal proximate to the device (the device canact as an MRI receive antenna to collect signal from local tissue)and/or that the device actually generates MRI signal itself, such as viasuitable hydro-based coatings and/or fluid (typically aqueous solutions)filled channels or lumens.

The term “MRI compatible” means that a device is safe for use in an MRIenvironment and/or can operate as intended in an MRI environment withoutgenerating MR signal artifacts, and, as such, if residing within thehigh-field strength region of the magnetic field, is typically made of anon-ferromagnetic MRI compatible material(s) suitable to reside and/oroperate in a high magnetic field environment.

The term “high-magnetic field” refers to field strengths above about 0.5T (Tesla), typically above 1.0 T, and more typically between about 1.5 Tand 10 T, such as 2.0 T and 3.0 T, for example.

The term “near real time” refers to both low latency and high framerate. Latency is generally measured as the time from when an eventoccurs to display of the event (total processing time). For near“real-time” imaging, the frame rate is typically between about 1 fps toabout 20 fps, and in some embodiments, between about 3 fps to about 7fps. The low latency required to be considered “near real time” isgenerally less than or equal to about 1 second. With respect to imaging,visualizations using near real time MR image data can be presented witha low latency, typically within between about 0.01 ms to less than about1 second, and with a frame rate that is typically between about 1-20fps. The MRI-guided interventional system can use the image signal datato dynamically present anatomy and one or more intrabody devices in thevisualization in near real-time.

The term “sterile,” as used herein, means that a device, kit, and/orpackaging meets or exceeds medical/surgical cleanliness guidelines, andtypically is free from live bacteria or other microorganisms.

The term “semi-rigid” refers to devices that have sufficient rigidity tohave a self-supporting fixed shape (typically straight linearcylindrical shapes) in the absence of applied bending forces but havesufficient flexibility to be able to bend or deflect without breaking inresponse to forces applied during insertion into or removal from atrajectory guide, then return to its original self-supporting shape uponremoval of the applied force(s).

The subject can be any subject, and may be particularly suitable foranimal and/or human subjects for e.g., animal studies and/orveterinarian or human treatments.

Some embodiments aspirate fluid from a target intrabody region such as,for example, a brain.

Embodiments of the invention can deliver therapies to the spine.

Embodiments of the invention can deliver therapies to treat or stimulatea desired region of the sympathetic nerve chain. Other uses, inside oroutside the brain, nervous system or spinal cord, include stem cellplacement, gene therapy or drug delivery for treating physiologicalconditions, chemotherapy, drugs including replicating therapy drugs.Some embodiments can be used to treat a patient with one or more tumors.

The term “fluid” with respect to fluid being withdrawn from a subjectrefers to soft tissue, foreign matter, biological matter includingcellular material and liquid in a subject.

The term “substance,” as used herein, refers to a gas or liquid fordelivery to a subject for treating or facilitating diagnosis of acondition and can include bions, stem cells or other target cells tosite-specific regions in the body, such as neurological, nerves or othertarget sites and the like. In some embodiments, stem cells and/or otherrebuilding cells or immune therapy products can be delivered into spine,brain or cardiac tissue. Embodiments of the invention can be used totransfer fluid to or from a heart wall via a minimally invasive MRIguided procedure, while the heart is beating (i.e., not requiring anon-beating heart with the patient on a heart-lung machine). Examples ofknown stimulation treatments and/or target body regions are described inU.S. Pat. Nos. 6,708,064; 6,438,423; 6,356,786; 6,526,318; 6,405,079;6,167,311; 6,539,263; 6,609,030 and 6,050,992, the contents of which arehereby incorporated by reference as if recited in full herein.

Embodiments of the present invention will now be described in furtherdetail below with reference to the figures. FIG. 1 illustrates anMRI-guided interventional system 10 with an MRI scanner 20, a clinicianworkstation 30 with at least one image processing circuit 30 c, at leastone display 32, an MRI compatible trajectory guide 50 and a fluidtransfer system 100. Embodiments of the fluid transfer system 100 can beutilized in a bore 20 b of a magnet 20M of an MRI scanner 20 of the MRIinterventional system 10.

The MRI system 10 can be provided as an MRI suite 10S that can have acontrol room 10C and a separate magnet room 10M holding the MR Scanner20 as is well known. However, there is no requirement for a separatecontrol room in some embodiments. Generally stated, MRI suites 10S canhave a control room 10C with MRI Scanner operating components such as anRF amplifier and control cabinet and a separate scanner room 10M holdinga (high field) magnet 20M in which a patient is placed for an MRIprocedure. MRI suites are enclosed in a Faraday shield (e.g., RFshielding) in order to electrically isolate sensitive MRI radioreceivers and prevent them from picking up RF signals other than thoseemitted by the patient under examination. An RF-shielded wall 10Rtypically separates the two rooms. For a typical MRI scanner room 10M,the RF shielding causes at least 100 dB of signal attenuation of signalsin the frequency range of 1 Hz to 150 MHz. Optionally, the MRI suite 10Scan be configured with fiber optic cables that are coupled to a userinterface that can allow a user to direct certain operational actionsusing the display 32. The display 30 can reside inside the scanner room10M. See, e.g., U.S. Pat. No. 9,610,048, the contents of which arehereby incorporated by reference as if recited in full herein.

The fluid transfer system 100 can be provided as components of a kit 100k held in one or more packages 101 as shown in FIG. 2.

The components shown in FIG. 2 can provide an MRI-safe fluid transfersystem and when used with a surgical navigation system can allow asurgeon to perform an entire medical procedure in an MRI scanner 20without requiring transport to another room.

The fluid transfer system 100 can include a device guide 110, a guidesheath 120, a stylet 125 slidably and detachably held by the guidesheath 120, and a cannula 130 coupled to flexible tubing 140. The fluidtransfer system 100 can also optionally include at least one syringe 170which may be provided in the kit 100 k or provided separately from thekit 100 k.

The flexible tubing 140 can have a proximal end 140 p and a distal end140 d. The proximal end 140 p can comprise a connector 142 that canattach to the syringe 170. The distal end 140 d can include a connector144 that can attach to the guide sheath 120. The flexible tubing 140with connectors 142, 144 can be provided in the kit 100 k integrallyattached to the cannula 130 as shown. However, the flexible tubing 140can be provided as a separate component that can be assembled onsite,i.e., for assembly prior to or during a medical procedure. The connector142 can be a standard (typically female) luer connector.

The kit 100 k can provide the stylet 125 pre-assembled to the guidesheath 120 as shown. The kit 100 k can provide the syringe 170pre-attached to the proximal end of the tubing 140 or the syringe 170,if provided in the kit, can be detached from the tubing 140.

Still referring to FIG. 2, the fluid transfer system 100 can alsoinclude an adapter 150, a depth stop 160 and a ruler 180. The ruler 180can provide graduated scales for positional measurements. The ruler 180can be a physical ruler that can be removed from the packaging 101 orthe ruler 180 can be provided as graduated markings formed or held on asurface of the packaging 101.

All components of the fluid transfer system 100 can be made of MRIcompatible materials, typically all made of polymeric materials. Theterm “MRI compatible materials” means that the materials arenon-ferromagnetic and do not magnetically interact with the magneticfield of the magnet. The components used in the MR Scanner room 10S arenon-metallic and do not generate heat due to RF coupling duringscanning.

The components of the kit 100 k that are inserted into the body, i.e.,brain, during the medical procedure can be configured to be clearlyvisible as voids (see, 220 v, FIG. 13) in images 200 generated from anMRI scan, which allows a clinician such as a surgeon to verify that theguide sheath 120, stylet 125 and/or cannula 130 are placed in a desiredposition in or at a target intrabody region prior to fluid transfer,such as aspiration.

As shown in FIG. 3, a targeting cannula 55 can be inserted into thetrajectory guide 50 that is coupled to a subject P for selecting adesired intrabody insertion path. The targeting cannula 55 can beremoved (as shown by the arrow) and replaced with the device guide 110as shown in FIG. 4. The targeting cannula 55 and device guide 110 canboth comprise outwardly extending lugs 56, 111 that are slidablyreceived in slots 52 in a tower member 51 of the trajectory guide 50. Asshown in FIG. 7A, the guide sheath 120 passes through the device, guide110 during insertion into the body, i.e., brain. The device guide 110has an open through channel with a diameter that has a close fit withthe outer wall of the guide sheath 120 so that the desired intrabodytrajectory can be maintained. The trajectory guide 50 typically providesboth X-Y adjustment and pitch and roll adjustment in order to accuratelyposition the targeting cannula 55 and guide sheath 120 at a desiredlocation within a patient. However, the trajectory guide 50 can haveother configurations and, in some embodiments, can provide only pitchand roll adjustment without X-Y adjustment. For additional discussion ofexamples of suitable trajectory guides, see U.S. Pat. No. 8,374,677, andco-pending U.S. patent application Ser. No. 15/934,165, the contents ofwhich are hereby incorporated by reference as if recited in full herein.However, it is noted that other trajectory guide configurations may beused and embodiments of the invention are not limited by the examples ofthe trajectory guides herein.

Referring to FIGS. 2, 5A and 5B, the adapter 150 can be attached to thetrajectory guide 50, in place of a removable cap. The adapter 150 has asufficiently large inner diameter passage or channel 150 c that allowsthe guide sheath 110 to slidably fit therethrough while locking theguide sheath 110 to the tower member 51 of the trajectory guide 50. Asshown in FIGS. 5A and 5B, for example, the adapter 150 has a lock member154 (shown as a thumb screw lock) that holds devices in position, i.e.,the guide sheath 120, on the trajectory guide 50 with the distal end 120d at the desired intrabody depth.

Referring to FIGS. 5C and 5D, the adapter 150 can have upper and lowerlock members 154, 152 and an open longitudinally extending throughchannel 150 c. The upper lock member 154 can cooperate with anelastomeric gasket 250 in the channel 150 c. The gasket 250 squeezes(compresses) against an outer wall of a device held in the channel 150c, i.e., the guide sheath 110, without kinking or denting the guidesheath 110 (FIG. 5A). The elastomeric gasket 250 can also increase agrip force with less tightening of the lock member 154 (i.e., thumbscrew) relative to the same lock member without such an elastomericgasket. In some embodiments, a ¼ rotation of the lock member 154 (i.e.,thumb screw) can provide about a 1-3 lb tightening/force, i.e., about a2.7 lb tightening/force, reducing the amount of turns required forsufficient locking/gripping.

Referring to FIG. 5D, the adapter 150 can include a cap 252 with acylindrical segment that resides in the open channel 150 c. The cap 252can have an open channel 252 c aligned with the open channel of theadapter 150 c. The cap 252 can hold the gasket 250 in place, alignedwith the upper lock member 154. The inner wall 252 w can taper inwardfrom a first diameter at the top of the cap 252 t to a smaller diameterproviding a chamfer 253 for piloting alignment of devices duringinsertion. The inner wall 150 w of the adapter body 150 b providing theopen channel 150 c can have an enlarged diameter in the segment holdingthe gasket 250 relative to the diameter of the open channel 150 c belowthe gasket 250.

The adapter 150 can also include a locking tab 255 with a bottom 255 bthat engages a circumferentially extending slot 52 in the trajectoryguide 50 (tower member 51) allowing for a “twist-lock” to affix theadapter 150 to the trajectory guide 50 and the lower lock member 152 canbe tightened to secure the adapter 150 to the tower member 51. Theadapter 150 can have a body 150 b with an inner wall 150 w that can besized and configured to provide a suitably sized diameter of the openchannel 150 c that slidably receives the tower member 51.

Referring to FIG. 2 and FIGS. 6A and 6B, the stylet 125 can have a tip125 t that is tapered to facilitate atraumatic insertion into thesubject. The taper can be over a tip length in a range of about 0.06inches to 0.11 inches. The stylet 125 can be hollow or solid, typicallywith a closed forward or tip end 125 t. When in the fully assembled andoperational position inside the guide sheath 120 shown, the stylet 125can be configured to exit the distal end of the guide sheath 120 d afixed distance that is in a range of about 1 mm to about 5 mm. FIG. 11shows that the stylet 125 can have a primary extruded polymeric body 125b with a hollow core 125 c and a closed tip 125 t. The stylet 125 canhave a length that is in a range of 9-13 inches, such as about 12inches. The extruded body 125 b can be semi-rigid with increasedflexibility relative to the cannula 130 and guide sheath 120 and can beformed of PEBAX with an outer diameter that is in a range of about 0.160inches and 0.212 inches and a wall thickness of about 0.025 inches.

The guide sheath 120 can be inserted into the subject (i.e., brain) totarget. It is semi-rigid. It encases or contains the stylet 125 with thestylet tip 125 extending external to the distal end 120 d of the guidesheath 120. The stylet 125 can be flexible and can be locked intoposition in the sheath 120 but can be removed once the surgeon verifiesthat the sheath 120 and stylet 125 are in the desired position in thetarget. The guide sheath 120 can provide a safe working channel in thesubject, i.e., brain, allowing the surgeon to insert and remove thecannula 130 as many times as needed without disturbing tissue more thanonce with the initial placement of the guide sheath 120. Since thestylet 125 locks on to the guide sheath 120, it can maintain itsrelative position to the guide sheath 120 even if the guide sheath 120is retracted or advanced relative to the tower (i.e., tubular) member 51of the trajectory guide 50.

Referring to FIGS. 2, 9A, 10A, 10B the cannula 130 with flexible tubing140 can be inserted into the guide sheath 120 as a unit so that fluidtransfer, i.e., aspiration may be performed. The cannula 130 andflexible tubing 140 are in fluid communication and form a conduit fortransferring fluid, i.e., removing aspirated fluid. The cannula 130 issemi-rigid. It can lock onto the guide sheath 120 in the same manner asthe flexible stylet 125. This allows the cannula 130 to maintain itsrelative position to the guide sheath 120 even if the guide sheath 120is retracted or advanced. The cannula 130 can have a distal end 130 dthat is flat.

The flexible tubing 140 can have a length that is in a range of 1-4 feetlong, more typically in a range of about 2 feet to 3 feet. The flexibletubing 140 is external to the subject P, free of any internal more rigidconduit and, when coupled to the guide sheath 120 while held by thetrajectory guide 50 coupled to the subject P, can have a lengthsufficient to extend out of a bore 20 b of a magnet 20 when the subjectis in the magnet, typically with a head of the subject residingproximate one end of the magnet bore 20 b (FIG. 12A) but is sufficientlyshort not to be able to drape to the floor of the scanner room when thepatient/subject is on a gantry or bed of the MR Scanner 20. For example,for a brain aspiration procedure, the trajectory guide 50 can be mountedto the skull of the subject P and the tubing 140 can extend a distanceof between 1-4 feet, allowing a clinician easy access to operate thesyringe 170.

An example workflow for an aspiration procedure carried out entirely inan MRI Suite 10 is summarized below.

Once the trajectory guide 50 is aligned to a desired trajectory, thetargeting cannula 55 can be removed (See FIG. 3). The device guide 110is then inserted into the trajectory guide 50 and locked it into abottom circumferentially extending slot 52 by twisting it (See FIG. 4).The adapter 150 is attached to the trajectory guide 50 and twisted toengage a (circumferentially extending) slot(s) 52 at the top of thetower member 51 (See FIG. 5A). The lock member 152 (shown as a lowerlock member, i.e., a bottom thumbscrew) is turned to secure it to thetower member 51 (See FIG. 5B). The guide sheath 120 and stylet 125, asan assembly can be obtained from the kit 100 k (FIG. 2). A visualconfirmation can be made to confirm that the Stylet tip 125 t isprotruding from the distal end 120 d of the guide sheath 120 (See FIG.6A). Review the depth measurement associated with the target aselectronically provided by the surgical navigation system 1000 (FIG.13). The ruler 180 (FIGS. 2, 6B) to measure corresponding distance onthe guide sheath 120. The depth distance from the stylet tip 125 t canbe measured (See FIG. 6B). The depth stop 160 can be placed at themeasured distance and locked to guide sheath 120 by tightening a lockmember 162, which can be a thumb screw (See FIG. 6B).

The guide sheath 120 and stylet 125 as an assembly 120 a can be insertedinto the trajectory guide 50 until the depth stop 160 bottoms out on oragainst a top surface 150 t of the adapter 150 (See FIGS. 7A and 7B).The upper lock member 154 (optionally a thumb screw) on the adapter 150can be tightened to engage the guide sheath 120 and hold the guidesheath 120 in place (See FIG. 7C).

As the components of the fluid delivery system 100 are MRI safe, scansmay be performed while the sheath-stylet assembly 120 a or sheath 120and cannula 130 are in position and/or being inserted. An MRI scan canbe performed to confirm tip position.

Referring to FIGS. 8A and 8B, the stylet 120 can have a connector 126that allows the stylet to be detached from the sheath 120. The connector126 can releasably engage a circumferentially extending hub 122 on aproximal end 120 p of the sheath 120. The connector 126 can comprise aclip 126 c with longitudinally extending handles (also interchangeablyreferred to as “legs”) 127. The longitudinally extending legs 127 canextend a distance above the hub 122. The hub 122 can have a greaterouter diameter than the primary body of the sheath 120 b and the primarybody of the stylet 125 b. The hub 122 can have a radially outwardlyextending ledge 122/that couples to lower ends of the legs 127. A usercan (gently) press against (depress) an upper end portion 127 u of thehandles 127, forcing the lower end portions 127 l to pivot outward andrelease the hub 122. The stylet 125 can be completely pulled out of theguide sheath 120.

Referring to FIGS. 9A and 9B, the cannula 130 can now be inserted intothe guide sheath 120 until a connector 144, which can be a clip 144 c,bottoms out on the hub 122 of the guide sheath 120. As shown in FIG.10A, the connector 144 can reside on a distal end of the tubing 140 d ora proximal end of the cannula 130 p. The clip 144 c can lock onto thehub 122. The clip 144 c can have a common configuration with the styletclip 126 c. The clip 144 c can have longitudinally extending handles(also interchangeably referred to as “legs”) 147. The longitudinallyextending legs 147 can extend a distance above the hub 122 in the lockedposition. The hub 122 can have a greater outer diameter than the primarybody of the cannula 130 b. A user can (gently) press against (depress)an upper end portion 147 u of the handles 147, forcing the lower endportions 147 l to pivot outward and release the hub 122. The cannula 130can be completely pulled out of the guide sheath 120.

Referring to FIGS. 10A and 10B, the flexible tubing 140 can have astandard (female twist-lock) luer connector 142 at the proximal end 140p. A syringe 170 (or other evacuation or pressure source) can beattached to the luer connector 142.

It is noted that although shown for use with a syringe 170, other fluidtransfer devices such as pumps for delivery or other vacuum devices suchas capillary action devices or tubing and cannisters connected to a wallvacuum source for aspiration may be used.

MR visualization may be used to monitor during a fluid transfer suchaspiration with the cannula in position attached to the flexible tubingand with the cannula 130 held by the guide sheath 120 which is coupledto the trajectory guide 50.

To retract the cannula 130, loosen the upper lock member 154 and pullthe guide sheath 120 back the desired amount. The upper lock member 154can then be retightened. The depth stop 160 can be repositioned byloosening the lock member 162 and sliding the depth stop up or down thensliding the guide sheath up or down until the depth stop 160 stops onthe top of the adapter 150 t. The lock member 162 of the depth stop 160can be retightened. The re-positioning of the cannula 130 and/or depthstop 160 can be repeated as many times as desired.

Embodiments of the invention overcome typical constraints of performingsurgical procedures while the patient is in an MR Scanner. Thecomponents also have novel designs that promote safety and ease of use.Embodiments of the invention provide a novel combination of materialsand sizing to address the MRI issues.

In some embodiments, the guide sheath 120 is semi-rigid. This allows itto maintain appropriate rigidity for accuracy of insertion while alsobeing able to resist being kinked or dented when locked by the lockmember 154. However, the configuration also allows it to bend so thatthe trajectory guide 50 will not experience a high amount of force inthe event of a bore collision. Furthermore, to allow for certaintargets, the size can be limited to a maximum outer diameter of 0.260″(19 Fr), which is lower than endoscopic trochars used in conventional.The maximal outer diameter may be smaller such as 14 Fr or 16 Fr.

The cannula 130 can be semi-rigid and have MRI compatibility (heatresistant, without magnetic pull, avoiding artifact generation forimaging) and can have sufficient flexibility so it can be slightly bentupon insertion, removal and reinsertion to avoid hitting the inside ofthe scanner bore. The cannula 130 can be inserted and removed severaltimes from the sheath 120 to flush it out during a surgical procedure,as desired.

The selection of material and wall thickness can be important tomaintain these desired properties, particularly given the sizeconstraints. Different combinations of materials and dimensions mayyield too rigid a guide sheath (which may make bore collisions unsafe),or too flexible a guide sheath (which compromises accuracy to target).The following tables illustrate example parameters of an examplesemi-rigid material. To maintain accuracy to a potentially deep target,it is preferred that there is no more than 3.5 mm of deflection at atarget 90 mm from the skull surface (Table 1). The 0.15-lb value is anestimate of lateral force applied by brain tissue during insertion of adevice. However, in order to deflect in the event of a bore collision,there should be a minimum of 20 mm (2 cm) of deflection with an appliedload of 4.0 lb, when the load is applied at 90 mm from where the sheathis supported. The 4.0-lb value is an estimate of the applied force ofthe bore on the device, as the scanner table is moved from the outsidetoward the bore center.

TABLE 1 Distance from Maximum Deflection (mm) Applied Load (lb)supported end (mm) 2.5 .15 90

TABLE 2 Distance from Minimum Deflection (mm) Applied Load (lb)supported end (mm) 20 4.0 90A material with an Elastic Modulus of 1.4-1.6 GPa (typically, about 1.5GPa) may be particularly suitable for components in a desireddimensional range according to some particular embodiments, as shown inTable 3.

TABLE 3 Deflection (mm) Deflection (mm) OD (in) ID (in) @ 0.15 lb, 90 mm@ 4.0 lb, 90 mm 0.260 .220 1.1 29 .233 .193 1.6 42 .208 .188 2.3 60

In some particular embodiments, the guide sheath 120 is made of extrudedtubing, such as PEEK tubing, with about a 0.020 inch wall thickness anda length that is in a range of about 8-15 inches, more typically a rangeof about 9-13 inches.

Referring to FIG. 6A, the guide sheath 120 can have a distal end portion120 d that is tapered over a short distance of about 0.125 inches tohave a smaller outer wall dimension at its tip 120 t relative to theouter wall dimension spaced apart from the tip 120 t. The guide sheath120 can have graduated scale of measurement markings 120m(interchangeably referred to as “measurement indicia”) starting with avalue above 0 or 1 (i.e., at 10 cm or greater, shown as starting at 15cm) residing a distance away from the tip 120 d and extending along atleast 25% of its length L, optionally in a range of 10 cm to 40 cm toits proximal end portion (FIG. 6A). The markings 120 m can start with ameasurement of 15 cm at a position that is 2-6 inches from the distalend 120 d and increase in measurement values toward the proximal end 120p. The guide sheath 120 can have a different length than the cannula130. The guide sheath 120 can be shorter than the cannula 130 (andstylet 125) in a range of about 1-3 inches, such as about 1 inch toabout 2 inches or 3-5 mm, when fully assembled. The guide sheath 120 canhave a maximal size of 19 Fr, such as 12 Fr, 14 Fr or 16 Fr, at leastfor the intrabody portion. The terms “F” and “Fr” interchangeably referto the French scale of size of a catheter as is known to those of skillin the art. The guide sheath 120 can have an outer diameter in a rangeof 0.208 inches and 0.260 inches, an inner diameter in a range of 0.168and 0.220 inches, and a wall thickness of about 0.020 in someembodiments. The guide sheath 120 can have a length in a range of about9-13 inches, in some embodiments.

The stylet 125 can be made of 70D durometer PEBA tubing with 0.025″ wallthickness that is tipped to create an atraumatic distal end 125 t. Thestylet 125 is sufficiently flexible so that it can be removed from theguide sheath 120 when the subject P is in the scanner bore, but the wallthickness prevents it from kinking when being bent (which would likelyprohibit it from being easily withdrawn out of the sheath 120). Thisallows the surgeon to remove the stylet to prepare for cannula insertionwithout having to move the scanner table out of the bore. The stylet 125can also bend without breaking or kinking in the event of the borecollision of the scanner.

The cannula 130 can have a maximal size of 10 F-16 F, such as about 10Fr, about 12 Fr, about 14 Fr or about 16 Fr, at least for the intrabodyportion. The cannula 130 can be made of (medical grade) polyimide tubingwith a wall thickness in a range of about 0.005-0.025 inches, optionallyin a range of about 0.009-0.010 inches. Polyimide at this combination ofID and wall thickness is semi-rigid. It provides good rigidity whilestill being flexible if bent. Again, this is a desirable property, as itallows the surgeon to insert the cannula 130 into the guide sheath 120,even when the trajectory guide's 50 clearance with the scanner bore 20 bis small. The wall thickness of the cannula 30 should not be made toothin, as the chance of kinking during bending, thereby obstructing flow,would increase. Also, the wall thickness should be substantial enough sothat the wall does not collapse under vacuum pressure during aspiration.In some particular embodiments, the cannula 130 has a small ID of about0.138 inches and an outer diameter of about 12 Fr, which allows a goodcross-sectional area for efficient aspiration of thick or viscous fluid.If the ID is too small, the suction efficiency may be compromised.

The cooperating configurations of the guide sheath 120, the cannula 130,and the stylet 125 promote ease of use and safety. The cannula 130 andstylet 125 can each have a clip-style connector 126 c, 144 c that allowsthem to easily lock with and detach from the guide sheath 120. The clips126 c, 144 c can be operated single-handedly, and they only require theuser to push them over the guide sheath's hub 122 to self-lock. Toremove either device from the guide sheath 120, the user need onlysqueeze the clip's handles 127, 147 and retract the device. This allowsthe user to insert and remove the cannula 130 and stylet 125single-handedly while the patient is in the scanner bore.

Also, when the stylet 125 is locked to the guide sheath 120, the stylettip 125 t protrudes a set distance, such as a range of 1-5 mm, moretypically a range of 3-5 mm, from the distal end 120 d of the sheath120. When the cannula 130 is locked into the guide sheath 120, itprotrudes the same amount as the distal end of the stylet 125 t. So, thecannula distal end 130 d is always the same position in the target asthe stylet distal end 125 d was. This allows the surgeon to confirm theposition once, exchange the stylet 125 with the cannula 130, and beassured that the cannula tip/distal end 130 d is in the same position asthe stylet tip 125 t. Furthermore, since the stylet 125 and cannula 130are serially locked to the guide sheath 120, the sheath 120 can beadjusted forward or backward if necessary, and the stylet 125 or cannula130 travels with it. Therefore, all positional adjustments need only bemade to the guide sheath 120.

Most aspiration cannulas are made of metal because the procedure isperformed in a completely open surgical environment. Therefore, they canbe highly rigid, which is an advantage in maintaining accurateplacement. The spatial constraints created by the patient's being in thescanner bore coupled with safety in the MR environment, and maintainingaccurate placement of the device, requires a unique combination ofrigidity and flexibility. Added to that are the requirements forefficient aspiration, and reduced chance of kinking.

Furthermore, ease of use while the patient is in the scanner bore isachieved by an interchangeable stylet 125 and cannula 130 system whichmaintains the position of the respective device tips during exchange.The position of the stylet 125 and the cannula 130 can always bemaintained relative to the guide sheath 120 when they are locked (fullyassembled) together. This allows for easy adjustment of the guide sheath120 when desired, without needing to confirm the position of the cannula130 or stylet 125 each time a positional adjustment (advance orretraction) is made.

FIGS. 12A and 12B illustrate that the stylet 125 and/or cannula 130 canbe semi-rigid so as to be able to bend to have a radius of curvature Rfrom its original straight linear shape, such as upon contact with or toavoid a wall of the bore of the magnet 20 b when mounted to thetrajectory guide 50 or upon removal from the trajectory guide 50. Evenif the bore 20 b of the magnet does not contact the top of the cannula130 or stylet 125, the flexibility of both components can allow asurgeon to withdraw/insert them from/into the guide sheath 120 whilekeeping the patient in the current bore position. The radius ofcurvature R of the guide sheath 120 can be a maximum of 6.7 cm to allowfor curvature of the semi-rigid component to stay within a clearance gapG between a top of the adapter 150 held by the trajectory guide 50 andthe wall of the bore that can be a minimum of 7 cm. The radius ofcurvature R of the cannula 130 and stylet 125 can be a maximum of 5.0 cmto allow for curvature of these components to be withdrawn/inserted witha clearance gap G1 (between the top of the guide sheath 120 and thescanner bore 20 b) that can be a minimum of 5.5 cm. This allows theguide sheath 120 to be very close to the scanner bore 20 b, while stillallowing removal/insertion of the stylet 125 and cannula 130. As shownin FIGS. 12A and 12B, the radius of curvature R can be measured from anon-bent linear line that is parallel to the tower 52 of the trajectoryguide 50.

FIG. 13 illustrates a display window of a display 32 from a surgicalnavigation system 1000 and having a user interface 30UI. The imageprocessing circuit 30 c can calculate, and direct the display 32 toprovide, a depth stop measurement output 160 m (depth stop distance) fora user to set the depth stop 160 on the guide sheath 120. Themeasurement provided can define a placement of the depth stop 160 at adistance from the stylet tip 125 t (FIG. 6A) to the desired location onthe guide sheath 120 rather than measured from the distal end of theguide sheath 120 d, in some embodiments.

In other embodiments, the measurement direction provided by thedisplay/image processing circuit 30 c can allow the user to measure fromthe distal end of the guide sheath 130 rather than where the stylet tipresides as the cannula distal end extends out of the distal end of thecannula a fixed known distance (i.e., the calculation of the depth stopposition on the guide sheath 130 is adjusted for this configuration, asthe actual target site reached will be based on the extension distance).The display 32 can also display images, i.e., MRI images 200 with theguide sheath 120, cannula 130 and/or stylet 125 shown as voids 220 v inthe image(s).

FIG. 14 illustrates an exemplary set of actions that can be used tocarry out an MRI-guided medical aspiration procedure. As shown, a set ofcomponents for an MRI guided aspiration medical procedure is provided.The set of components being MRI compatible and comprising: a deviceguide; a semi-rigid guide sheath with measurement indicia configured toslidably extend through the device guide; a stylet releasable coupled tothe guide sheath and extending a fixed distance out of a distal endthereof; and a cannula coupled to flexible tubing (block 500).

The device guide is attached to a trajectory guide mounted to a subject,the trajectory guide defining an entry trajectory axis into the subjectto a target site (block 510).

A depth stop is placed at a desired location on the guide sheath, thedesired location associated with measurement indicia calculated to placea distal end of the stylet and a distal end of the cannula at the targetsite when the guide sheath is attached to the trajectory guide (block520).

The guide sheath and stylet, coupled together as an assembly, areinserted through the open channel of the device guide (block 530).

The stylet is removed from the guide sheath and the cannula is theninserted into the guide sheath so that a distal end thereof resides atthe target site (block 540).

A syringe or other vacuum source is attached to the flexible tubing andfluid from the target site is aspirated through the cannula and theflexible tubing (block 550).

While the devices have been described herein primarily with reference toMRI-guided insertion and infusion procedures, in some embodiments thedevices can be used in procedures without MRI guidance.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. The invention is defined by the following claims, withequivalents of the claims to be included therein.

That which is claimed is:
 1. A surgical fluid transfer systemcomprising: a device guide comprising an axially extending open throughchannel; a semi-rigid guide sheath, wherein the guide sheath isconfigured to slidably extend through the open through channel of thedevice guide, wherein the guide sheath has an axially extending openthrough channel with opposing proximal and distal ends, wherein theguide sheath has a length that is longer than a length of the deviceguide, wherein the guide sheath comprises a radially outwardly extendinghub adjacent the proximal end, and wherein, in position, a distal end ofthe guide sheath extends a distance into a subject while the proximalend is external to the subject; a stylet releasably coupleable to theguide sheath, wherein, when fully assembled to the guide sheath, thestylet extends through the open through channel of the guide sheath andhas a distal end that extends a distance out of the distal end of theguide sheath, wherein the stylet comprises an extruded polymeric bodywith a hollow core and a solid tapered tip, and wherein the styletcomprises a proximal end portion with a connector that releasablyattaches to the hub; and a cannula coupled to flexible tubing andcomprising longitudinally opposing proximal and distal ends, wherein thecannula is semi-rigid, wherein the flexible tubing has a distal end thatis sealably coupled to the proximal end of the cannula, wherein, in use,the flexible tubing and the proximal end of the cannula reside externalto the subject, wherein the cannula is releasably interchangeablycoupleable to the guide sheath in place of the stylet, and wherein, inposition, the cannula extends through the guide sheath and the distalend extends a distance out of the distal end of the guide sheath.
 2. Thesystem of claim 1, wherein the guide sheath comprises measurementindicia on an external wall thereof, and wherein the measurement indiciacomprises a numerical scale of distance that increases in a directiontoward the proximal end of the guide sheath.
 3. The system of claim 1,wherein the connector is a clip with longitudinally extending handleseach configured to have a straight linear length that extends a distanceabove the hub and that terminates at lower end portions adjacent asmaller transverse section of the hub, wherein the lower end portionsturn inward and face each other across the hub, and wherein upper endportions thereof flex inward to pivot the lower end portions outward todisengage the hub.
 4. The system of claim 1, further comprising a depthstop slidably held by the guide sheath that defines a fixed distance asthe distance that the distal end of the cannula extends out of thedistal end of the guide sheath.
 5. The system of claim 4, wherein thedistance is in a range of about 3-5 mm.
 6. The system of claim 1,wherein the flexible tubing comprises a guide sheath connector on adistal end portion thereof that releasably attaches to the hub.
 7. Thesystem of claim 6, wherein the guide sheath connector is a clip withlongitudinally extending handles that are parallel to and are spacedoutward a distance from an outer surface of the guide sheath and thatextend a distance above the hub and terminate at a lower portion of thehub at lower end portions that turn inward toward the hub, and whereinupper end portions thereof flex inward to pivot the lower end portionsoutward to disengage the hub.
 8. The system of claim 1, furthercomprising an adapter with a longitudinally extending through channel,the adapter comprising a unitary body with upper and lower spaced apartlock members, wherein the upper lock member communicates with aninternal gasket that extends a sub-length of the adapter, and whereinthe guide sheath is configured to extend through the adapter and onlythe upper lock member is configured to lock against the guide sheath. 9.The system of claim 8, further comprising a depth stop that slidablycouples to the guide sheath and is adjustable along a length of theguide sheath, wherein the depth stop abuts a top surface of the adapterto hold the guide sheath in a fixed position.
 10. The system of claim 1,wherein the device guide, the guide sheath, the stylet and the cannulawith the flexible tubing are all Mill compatible polymeric devicesprovided in a kit for an aspiration procedure.
 11. The system of claim1, wherein the cannula is formed of medical grade polyimide tubing witha wall thickness in a range of about 0.005-0.025 inches, and wherein thecannula has a maximal intrabody size in a range of about 10 Fr-16 Fr.12. The system device of claim 11, wherein the wall thickness of themedical grade polyimide tubing is in a range of about 0.009-0.010inches.
 13. The system of claim 1, wherein the guide sheath is formed ofextruded medical grade PEEK and has a maximal outer diameter in a rangeof 12 Fr and 19 Fr, and wherein the guide sheath has a length in a rangeof 10-16 inches, a wall thickness of about 0.020 inches, and an innerdiameter in a range of 0.168 inches and 0.220 inches.
 14. The system ofclaim 1, wherein the guide sheath comprises a graduated scale ofdistance extending over a sub-length of a body of the guide sheath witha segment adjacent the distal end being devoid of the graduated scaleand with the graduated scale providing units of distance that increasein a direction toward the proximal end of the guide sheath.
 15. Thesystem of claim 1, wherein the guide sheath comprises a graduated scalethat starts at a distance value that is greater than 10 cm at a locationspaced apart from the distal end in a range of 1-8 cm therefrom andextends in increasing order to the proximal end.
 16. The system of claim1, further comprising a guide sheath connector on the distal end of theflexible tubing or the proximal end of the cannula that is configured asa clip with longitudinally extending handles that are parallel to andspaced outward a distance from an outer surface of the cannula and thatextend a distance above the hub and that terminate at a lower portion ofthe hub at lower end portions that turn inward toward the hub, andwherein upper end portions of the handles flex inward to pivot the lowerend portions outward to disengage the hub.
 17. A surgical fluid transfersystem comprising: a device guide comprising an axially extending openthrough channel; a semi-rigid guide sheath, wherein the guide sheath isconfigured to slidably extend through the open through channel of thedevice guide, wherein the guide sheath has an axially extending openthrough channel with opposing proximal and distal ends, wherein theguide sheath has a length that is longer than a length of the deviceguide, wherein the guide sheath comprises a radially outwardly extendinghub adjacent the proximal end, and wherein, in position, a distal end ofthe guide sheath extends a distance into a subject while the proximalend is external to the subject; a stylet releasably coupled to the guidesheath, wherein, when fully assembled to the guide sheath, the styletextends through the open through channel of the guide sheath and has adistal end that extends a distance out of the distal end of the guidesheath, wherein the stylet comprises an extruded polymeric body with ahollow core and a solid tapered tip, and wherein the stylet comprises aproximal end portion with a connector that releasably attaches to thehub; a cannula coupled to flexible tubing and comprising longitudinallyopposing proximal and distal ends, wherein the flexible tubing has adistal end that is sealably coupled to the proximal end of the cannula,wherein, in use, the flexible tubing and the proximal end of the cannulareside external to the subject, wherein the cannula is releasablyinterchangeably coupled to the guide sheath, and wherein, in position,the cannula extends through the guide sheath and the distal end extendsa distance out of the distal end of the guide sheath; an adapter with alongitudinally extending through channel, the adapter comprising upperand lower spaced apart lock members, wherein the guide sheath isconfigured to extend through the adapter and the upper lock member isconfigured to lock against the guide sheath; and a trajectory guideadapted to mount to the subject, the trajectory guide comprising atubular support member with an open through channel that holds thedevice guide and receives a bottom portion of the adapter.
 18. Anaspiration system, comprising: a trajectory guide; a device guide heldby the trajectory guide; an adapter with a longitudinally extendingthrough channel and upper and lower lock members; a semi-rigid polymericguide sheath comprising opposing proximal and distal ends and alongitudinally extending open through channel, wherein the guide sheathfurther comprises an outer wall with an outwardly extending hub adjacentthe proximal end, wherein the guide sheath extends through the deviceguide and adapter, and wherein the upper lock member of the adapter islockable against the guide sheath; a stylet with a guide sheathconnector on a proximal end portion thereof releasably attachable to theguide sheath, wherein the stylet has a polymeric body with a closedtapered tip that extends a distance out of the distal end of the guidesheath; and a semi-rigid polymeric cannula coupled to flexible tubing,wherein a distal end of the flexible tubing or a proximal end of thecannula comprises a guide sheath connector that is also,interchangeably, releasably attachable to the guide sheath in place ofthe stylet, and wherein, when coupled to the guide sheath, a distal endof the cannula extends a distance out of the distal end of the guidesheath.
 19. The system of claim 18, wherein the distal end of thecannula and the tip of the stylet extend out of the distal end of theguide sheath a fixed common distance in a range of about 3-5 mm.
 20. Thesystem of claim 18, further comprising a syringe coupled to a proximalend of the flexible tubing to thereby allow a user to aspirate fluidfrom the subject through the cannula and flexible tubing.
 21. The systemof claim 18, wherein the stylet comprises an extruded polymeric bodywith a hollow core with an open proximal end and a solid tapered tipdefining the closed tapered tip.
 22. The system of claim 18, wherein thecannula comprises a body of medical grade polyimide tubing with a wallthickness in a range of about 0.005-0.025 inches, and wherein thecannula has a maximal intrabody size of about 10 Fr-16 Fr.
 23. Thesystem of claim 18, further comprising a depth stop on the guide sheathresiding below the hub, wherein the upper lock member communicates withan internal gasket that extends a sub-length of the adapter.
 24. Thesystem of claim 18, wherein the outer wall of the guide sheath furthercomprises external measurement indicia comprising a graduated scalethereof provided with units of distance that increase in a directiontoward the proximal end of the guide sheath.
 25. A method of removingfluid from a target intrabody site, during an MRI guided surgicalprocedure, comprising: providing a set of MRI compatible componentscomprising a device guide, a semi-rigid guide sheath configured toslidably extend through the device guide, a stylet releasably coupled tothe guide sheath and extending a fixed distance out of a distal endthereto, and a cannula coupled to flexible tubing; attaching the deviceguide to a trajectory guide mounted to a subject, the trajectory guidedefining an entry trajectory axis into the subject to a target site;placing a depth stop at a desired location on the guide sheath, thedesired location associated with measurement indicia calculated to placea distal end of the stylet and a distal end of the cannula at the targetsite when the guide sheath is attached to the trajectory guide, whereinthe guide sheath comprises measurement indicia with distance valuesincreasing in a direction toward a proximal end portion of the guidesheath; inserting the guide sheath and stylet, coupled together as anassembly, through an open channel of the device guide; removing thestylet from the guide sheath, bending the stylet relative to the deviceguide during the removal to clear a wall of a bore of a magnet of an MRIscanner; then inserting the cannula into the guide sheath so that adistal end thereof resides at the target site; and removing fluid fromthe target site through the cannula and flexible tubing while thesubject is in a magnet of an MR Scanner during the MM guided surgicalprocedure.